1. Field of the Invention
The present disclosure relates to an image forming apparatus such as copying machines, printers, and facsimile apparatuses configured to form a toner image on a recording material using an electrophotographic system or an electrostatic recording system. More specifically, the disclosure relates to an image forming apparatus having an intermediate transfer belt configured to carry a toner image to be transferred to a recording material.
2. Description of the Related Art
Examples of image forming apparatuses of the related art include a configuration in which a toner image formed on a photosensitive drum as an image carrier is transferred to a recording material at a transfer nip portion.
At the time of conveying the high-rigidity recording material such as a thick paper, when a trailing end of the recording material leaves a covey roller or a leading end of the recording material enters the transfer nip portion, the posture of the recording material is changed and hence the trailing end of the recording material is flipped upward. When the leading end of the recording material is at the transfer nip portion, the recording material vibrates due to a shock imparted by a contact to other portions of the trailing end of the recording material caused by the change of the posture of the recording material, which may cause a transfer failure. In order to reduce the shock, a configuration in which a shock absorbing plate formed of a plate member having a resiliency and rigidity such as a synthetic resin is arranged on a lower surface of a pre-transfer upper guide so as not to come into contact with the pre-transfer lower guide is exemplified (Japanese Patent Laid-Open No. 2006-089232). In this configuration, when the high-rigidity recording material such as a post card is passed through, the shock absorbing plate is resiliently curved upward along the flip-up of the recording material when the shock absorbing plate leaves the transfer roller, so that the impact imparted on a transfer portion may be alleviated.
Examples of the image forming apparatuses in recent years include a configuration in which a toner image formed on a photosensitive drum, which is an image carrier, is transferred from the photosensitive drum to an intermediate transfer belt, and the toner image is transferred from the intermediate transfer belt to the recording material to form the toner image on the recording material.
Then, in the configuration in which the intermediate transfer belt is used, the leading end of the recording material is likely to come into contact with the intermediate transfer belt. When the leading end of the recording material comes into contact with the intermediate transfer belt, there is a case where an impact is propagated to the transfer nip portion and then to an image forming portion via the intermediate belt, thereby generating defective images.
In order to prevent such a phenomenon, a configuration in which the shock absorbing plate as described above is used and a distal end of the shock absorbing plate is brought near to the transfer nip portion to avoid easy contact of the recording material to the intermediate transfer belt. However, depending on the distance between the distal end of the shock absorbing plate and the transfer nip portion, the shock absorbing plate and the intermediate transfer belt are likely to come into contact with each other due to vibrations of a surface of the intermediate transfer belt during rotation, and the image on the intermediate transfer belt is likely to be distorted. Therefore, even when the leading end of the recording material and the intermediate transfer belt come into contact with each other, countermeasures for the intermediate transfer belt to reduce the shock applied by the recording material are needed.